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Optical Communications: Lighting our Way to Development

In the last decade, we have witnessed one of the most significant technology revolutions in human history. Telecommunications, particularly mobile telephony, has transformed several nations that have long been languishing at the bottom of the development pyramid. As per GSMA (Groupe Speciale Mobile Association), there are over 5 billion mobile connections in the developing world today increasing at the rate of 17 per second! Mobiles have literally reached communities “where no man has gone before”, either due to the absence of roads or on account of other socio-cultural distances that were hard to bridge. In developing countries like India, there are more people with mobile phones today than with a bank account. Thanks to mobile communications, services such as healthcare, financial services and education will eventually become available to these billions of people.

However, while the role of wireless technologies is widely recognized, and terms like “2G/3G/4G/GSM/CDMA/LTE” have now entered common parlance, the importance of light-based technologies in sparking the mobile economy has surprisingly gone unnoticed.

“Mobile is evidently wireless, so what does light have to do with it?” you might ask. While it’s true that there is no wired link from your mobile phone to the neighboring cell tower, optical fiber technology forms the backbone of today’s telecom networks. 95% of all kinds of telecommunications traffic, whether emanating from land phones, mobile phones or modems, eventually land on an optical fiber network at a cell tower, a telephone exchange or at a local service provider office. Optical networks utilize fiber cables comprising hundreds of thin strands of special transparent glass that are laid underground and hence remain hidden from public view. Telecom operators use laser-based optical networking equipment to aggregate voice and Internet traffic from the neighborhood and transmit them digitally as modulated light waves on these glass fibers. While laying these fiber cables is a long and laborious process, optical fiber has a shelf life of a few decades, since the same fiber can be used to offer higher and higher speeds by upgrading the associated optical networking equipment without needing to re-invest in the fiber plant. For example, a single fiber strand is capable of carrying tens of terabits of traffic today through modern techniques called dense lightwave multiplexing (DWDM) and coherent optical processing. Without such light-based technologies, the telecommunication networks of today cannot be scaled to deliver thousands of services to billions of subscribers using mobile or home broadband networks. Apart from offering virtually unlimited bandwidth, transmission over optic fiber is also more reliable, since it’s not affected by impairments such as electromagnetic interference and weather. Since signal losses in a fiber are very low, data can be economically transmitted over thousands of kilometers without having expensive electronics equipment deployed along the way for signal regeneration. Due to these advantages optical fiber is already the medium of choice for national long distance and international connectivity, and over the last decade has found its way into city-wide networks as well.

The global telecom sector is on the cusp of a broadband revolution. While the first phase of telecom growth was driven by voice services, the current phase is data dominated. The advent of smartphones, high-definition video and “always on” social media applications have made things even more exciting for optical communications. The deluge of broadband data and the stringent quality requirements of the more popular “visual” applications have made it essential for telecommunication carriers to take optical fiber links closer to their subscribers’ homes (FTTH – Fiber to the Home). Unlike wireless access, with optical connectivity there’s no spectrum congestion due to a large number of users sharing the same limited set of frequencies. The quality of service experience and access speeds on FTTH will therefore be significantly better compared to wireless infrastructure. Although many governments are working towards identifying and auctioning new spectrum for mobile communications, it will continue to be a scarce resource for years to come. Wireless broadband can ensure connectivity but eventually it will be optical fiber that delivers capacity.

This primary role of optical fiber in delivering broadband is the reason why governments, both in developed and developing countries, are taking increasing interest in building country-wide optical fiber networks for broadband connectivity. For example, the Indian government is investing billions of dollars to create a National Optical Fiber Network (NOFN) that will extend optical fiber connections to every village household or at least up to its 250,000 local village offices. Australia is making rapid progress with its National Broadband Network (NBN) which intends to deliver the country’s first national wholesale-only, open access broadband network to all Australians. Similarly, Bangladesh is implementing the “1000 Union Parishad” project for extending nationwide optical fiber connectivity to villages. Similar efforts are also underway in Philippines, Indonesia, Sri Lanka, Thailand, Malaysia and many other countries. Optical fiber infrastructure is becoming as crucial as consumer utilities like electricity, water and gas because of its potential to deliver a host of applications like telemedicine, e-governance, e-learning and online banking to remote villages. Hence besides laying new optical fiber cables, large utility providers such as railways, oil and gas, power transmission companies are also unbundling their abundant fiber resources and making them available for broadband delivery to their citizens.

Optical communications appears to be finally getting its due as a critical enabler for delivering affordable broadband connectivity to under-served populations thus facilitating economic development, essential service delivery and poverty alleviation around the globe.

Kumar N. Sivarajan is the Chairman of TSDSI, India’s telecommunication standards development organization. He is also the CTO of Tejas Networks, India’s leading optical equipment company that he co-founded in 2000. Previously, Kumar was with the Indian Institute of Science, Bangalore and the IBM Watson Research Center, New York. Kumar is a co-author of the textbook `Optical Networks: A Practical Perspective’. He received the prestigious IEEE Baker Prize Paper Award in 1997. Kumar holds a Ph.D. in Electrical Engineering from Caltech, Pasadena, USA and is a distinguished alumnus of IIT, Madras.